In-flight entertainment (IFE) systems are deployed onboard aircraft to provide entertainment for passengers in a passenger cabin. Video display units are used to deliver services, such as audio/video-on-demand (AVOD), web browsing, email, voice-over-internet protocol (IP), shopping, games, and the like for the IFE.
Typically, in-flight television programs are provided through personal video display units (VDUs) installed at each passenger seat or on overhead VDUs that can be spaced over groups of seats. Audio content is provided through personal headsets connected to audio jacks installed in the seats, usually in the armrest of the seats. When installed at each passenger seat, all seats can be networked to one or more centralized content servers to receive video/audio content. Ethernet is an example communications network that can be used for data packet communications between the content server(s), which is usually installed somewhere in an airplane hidden from the passengers view, and the VDUs.
In some conventional systems, for example, the system illustrated in FIG. 1, video display units (VDUs) 120 can be connected in a logical ring network connected to a head-end server 110. Each link in the network loop may be bidirectional, thus allowing at least two non-overlapping data paths between a network node (e.g., VDU) to any other node (e.g., VDU) for redundancy.
To provide media content, the VDUs 120 are fed a steady stream of media/data from either a local storage subsystem or from the head-end server 110. In some systems all content is stored at the head-end server 110, in others all content is stored locally at the seat-back client 120.
A typical IFE operator's requirement is that each VDU 120 (client) has access to a total data volume in the order of 1 terabyte (TB). If the data is stored at one or more (for redundancy) head-end servers 110, then the cost to develop, deploy, and operate a high-performance server is necessary, for example, to handle worst-case concurrent demand. On the other hand, if the entire data volume is stored locally at each client 120, then the cost, per client 120 would be prohibitive due to the large storage requirement and the number of clients needed.
Between these extremes, there is a continuum of implementation choices for state-of-the-art in conventional systems. For example, an operator may choose to store popular data locally at the VDU (client 120) and infrequently accessed data at the server (head-end 110), thus possibly reducing the server's high-performance requirement due to lowered effective demand. However, a hybrid implementation is often more costly than just a linear combination of the two extremes' due to the high non-recurring cost of new functional development for two devices.
Alternatively, the IFE operator may choose to accept a certain level of service outage (probabilistically) and undersize the server's performance capacity to reduce server cost. If a new passenger's request exceeds the server's instantaneous spare capacity, it may be rejected. This approach may incur a less tangible cost associated with lowered quality-of-experience for the passengers. Accordingly, improved methods and systems for content distribution may be desired.